Airworthiness Directives; Empresa Brasileira de Aeronautica, S.A. (EMBRAER) Model EMB-120 Series Airplanes

摘要

This document proposes the adoption of a new airworthiness directive (AD) that is applicable to certain EMBRAER Model EMB-120 series airplanes. This proposal would require repetitive inspections to detect cracks in the wing rib-to-skin support brackets (shear clips), and replacement of cracked brackets with new or serviceable brackets. This proposal also would require the eventual replacement of certain brackets with new brackets, which would terminate the requirement for the inspections. This proposal is prompted by reports of cracks in the wing rib-to-skin support brackets in both the lower and upper skin of the wings. The actions specified by the proposed AD are intended to prevent cracking of those support brackets, which can subsequently lead to the loosening of the rivets in the wing skin, leakage of fuel through the rivet holes, and, ultimately, the reduction of the structural integrity of the wing.